Hydraulic piston engines are used, for example, in hydrostatic-mechanical torque-splitting transmissions for the hydraulic power branch in order to continuously vary the gear ratio of the transmission. For this purpose, the hydraulic piston engines need adjustment devices by means of which the stroke volume of the piston engines can be adjusted.
DE 42 06 023 A1 discloses a continuously variable hydrostatic-mechanical torque-splitting transmission having hydraulic piston engines and adjustment devices by means of which the piston engines can be adjusted continuously. The adjustment device comprises control elements by means of which the piston engines can be controlled. In order to protect the system from overload, the adjustment device has a high-pressure relief valve by which the maximum pressure can be limited. When the high-pressure relief valve is activated, energy is converted into heat which has to be dissipated via a cooler.